This study was funded by the NCI in the autumn of 1992. Enrollment into the pilot phase began in early 1994 and full-scale enrollment was initiated in October of 1995. The PLCO trial is two-armed randomized trial in which 148,000 individuals will receive either screening or usual care. The University of Utah will enroll 13,000 research subjects. Ten thousand eight hundred will be screened at the University of Utah's GCRC and 2,800 will be screened at a satellite location in Boise, Idaho. As of April 1, 1999, 11,745 subjects have been enrolled and enrollment is expected to be completed by September of 1999. Over the next five years the incidents of the cancers under study in the two groups (screened or not screened) will be compared. This phase of the study is just beginning.